Generally, the data, arising from these representations, are correlated with cartographic data. They can be of meteorological or topological type, for example. Within the framework of the device according to the invention, the graphical representations of the aerial environment are servoed according to a reference cycle of calculations of the avionics computer and overlaid on a mapping of the terrain.
Currently, equipment dedicated to graphical representations of the aircraft-related environment and of the aircraft-independent environment exists in aircraft such as civil and military airplanes or helicopters.
The systems for representing the aircraft-related environment depend on data specific to the aircraft, such as the system data, the trajectory, the altimetry data or the resources of said aircraft. The pilot is constantly informed of these data. These data are critical for navigation and are calculated and refreshed at each cycle of calculations of the avionics computer. They can, notably, serve for other applications which require information specific to the aircraft in the guise of input data to perform other calculations. These data may typically be the heading of the aircraft or its position in space, for example.
To enable the pilot to navigate with a knowledge of the environment so as to minimize the dangers, the data related to the environment of the aircraft are correlated with the environmental data independent of the aircraft. These data can be of the topological or meteorological type, for example. They can arise from a database, such as terrain data or be captured, calculated and processed in real time, such as meteorological data.
Correlation of these data makes it possible, for example, to ascertain and to predict, for a determined heading and a known trajectory, the potential dangers related to the situation of the aircraft in its outside environment. The prediction is evaluated in the near future with the assumption that the heading and the trajectory of the aircraft remain unchanged. Viewing screens or alarms are customarily used to alert the pilot.
One of the main benefits of such functions is to evaluate potential risks, notably, of collisions, of strong turbulence or else of lightning which would cause a decline in flight safety.
Several systems exist for representing the aircraft-related environment, which each depend on the data specific to a given application.
An exemplary existing system for analyzing environmental data is the WXR system, the trade name given to the product developed and marketed by Rockwell Collins, and standing for “Weather Radar System”. This equipment is used in numerous aircraft. It includes a radar antenna, which permanently scans an angular sector situated in front of the carrier over a parametrizable distance. This equipment analyzes the atmosphere to recover meteorological data and provide them to the pilot.
On the basis of the data acquired in real time, the WXR equipment is capable of providing digitized meteorological information to the other systems of the carrier. This information then makes it possible, in the case of display systems situated in the flight cabin, to depict the sector scanned on a screen. The crew obtains the meteorological information in relation to the position of the carrier.
Moreover, another exemplary case of such systems is the TAWS system, the acronym standing for “Terrain Awareness Warning System”. The system has been developed and marketed by Thales in collaboration with L-3 Communications, the name of the product is called T2CAS.
More generally, TAWS is a system which, with respect to altimetry data, arising from a numerical database, generates a graphical display and if appropriate audible alarms on the basis of a calculation which takes into account:                the position of the carrier, as well as various flight parameters notably its speed and its heading;        the extrapolations of the trajectory of the carrier in order to perform prediction calculations;        the characteristics of the carrier in terms of performance, notably as regards the emergency climb phases at maximum performance.        
On completion of this calculation, the TAWS advises the crew, graphically or in the form of audible alarms, of:                the altitude slice in which the carrier is situated in relation to the terrain round about.        the zones of the terrain which may over a short time scale endanger the safety of the flight if the crew does not modify the trajectory of the carrier        the zones of the terrain which endanger the safety of the flight if the crew does not immediately modify the trajectory of the carrier        
The TAWS is a function which is embedded in real-time avionics computers.
Another exemplary application is the terrain topology cartographic representation system. This system, by means of a known numerical database, constructs a graphical representation of the terrain and its attributes, such as shade, vector data and obstacles.
In particular, in aircraft, the graphical representation of the terrain is servoed for a given calculation cycle by the carrier's current position and with respect to its heading. Several modes of representing the terrain and positioning of the carrier on the terrain are available depending on the operational contexts.
As regards the harmonization of the graphics, arising from the various applications, the structure of the data and the discretization of the information depend notably on each application and the protocols used. For example the TAWS and WXR applications structure their digital data according to radials. This data structure complies with the ARINC 453 protocol making it possible to provide, by means of generating images, formatted frames originating from calculation means.
Moreover, the cartographic function uses another mode of data structure.
Within this framework, FIG. 1a represents the digitization of information collected, in space or from a database, in the form of radials. A radial 5 is oriented along an angle close to the heading of the aircraft. In the TAWS application, the radial possesses a range 3 corresponding to the most distant point in the digitized zone. This radial includes a certain number of points 1. Each of the points digitizes an item of information, notably calculated on the basis of the altitude of the measured point. The point represents notably a danger for the aircraft in the near future if the heading does not change. The latter possesses a color code which indicates to the pilot the potential danger in the direction of the radial. The radials possess a spread, represented by an angle 2. At a given distance from the aircraft, the point discretizes the danger in a perimeter included in the angle 2 and between the point downstream and the point upstream of the point considered.
The actual representations of the data arising from the various applications use colors. The pilot can thus judge a zone dangerous or risk free as a function of the color code assigned.
The TAWS application refreshes a set of radials in a determined calculation time and presents them to the pilot in graphical form. FIG. 1b represents a set of radials digitizing a part of the space situated in front of the aircraft.
For a cycle C0 of the avionics computer, the resources being shared between the various applications, a certain number of radials can be calculated and displayed. In the example of the TAWS application, at each cycle C0, four radials can be calculated and displayed. For example, an image, representing the TAWS data, is considered to be formed of 400 radials. A calculation cycle, denoted C1, corresponding to 100 real-time cycles of the avionics computer, is necessary in order to consider that the image is entirely refreshed on the screen. On finishing the cycle C1, the complete representation of the TAWS data is calculated and displayed, as a function of the heading and position of the aircraft. In the cycle C1, the graphical representation of the TAWS data is redisplayed in parts at each cycle C0, in the example in groups of four radials, on a viewing screen, to the pilot. This redisplay is carried out with the aircraft heading and position information corresponding to the first of the 100 cycles C0 which make up a cycle C1.
In the case of changes of heading of the aircraft, in particular when turning, there may be a de-synchronism between the orientation of the representation of the TAWS data and the actual heading newly calculated after a cycle C0.
FIG. 2 represents a graphic of an example of the TAWS application. It represents an angular sector 22 digitized by points of each radial. Each point represented includes a color information cue relating to danger, said danger being estimated on the basis of the aircraft's altitude extrapolated into the near future. This angular sector therefore includes zones of various hues or colors. This zone covers a wide angle centered on the heading of the aircraft 23. Certain hues 20 represent a danger if the aircraft steers towards this zone, other hues 21 signify that no danger of collision is visible in this direction.
During the cycle C2, another application, such as the cartographic function, is capable of refreshing the whole of the geo-referenced map, on the basis of an embedded database, and to display the representation on a viewing screen.
In the example of the cartographic function application, cycle C2 is equal to C0. Thus the map is calculated and displayed, as a function of the heading and position of the aircraft, at each elementary cycle C0.
Within a framework of another application, cycle C2 could be greater than C0.
FIG. 3 represents a mapping 30 of the relief that the aircraft is overflying. The zone 31 represents a relief which could be a mountain or a hill, the zone 32 represents a space of low relief.
The drawback, of the de-synchronism of operation of the various applications, is to provide the pilot with information originating from several applications in different data refresh time bases.
Currently, the cycles of calculations, notably of systems for the graphical representation of multiple environments which may or may not be related to the aircraft, are independent. Each application is dedicated to a given function and their integration requires as many graphical resources as there are applications.
The drawbacks of these solutions, such as developed, are their relative independence and their exclusive use which makes it necessary for example to integrate as many viewing screens as applications into the flight cabin. For example, each of the aforementioned three applications, the mapping application, the meteorological application, and the altimetry application, possesses dedicated graphical resources and a dedicated display.
The exclusivity of the applications requires the pilot either to manually change graphical representation on one and the same screen according to the application, or to track various screens during the piloting phase.
Another drawback is the refreshing of the data of each application which depends on the real-time constraints related to the calculational load of each application. The pilot is thus constrained, with full knowledge of the facts, to integrate this differentiation of data refreshing according to the application that he is consulting. If a reference calculation time cycle of the avionics computer is considered, each application servos its own data, calculationally or graphically, in accordance with its own specific number of cycles. The elementary cycle which represents the smallest real-time calculation cycle of the avionics computer allowing the calculation of the heading and position of the aircraft and the display of aircraft-related graphical data is defined in this patent, this cycle is denoted C0 hereinafter.
An operating advantage for the pilot is of being afforded a common display of the various applications when the latter exhibit topological or geographical similarities. For example, the representation of the TAWS data and the representation of the cartographic function could be overlaid. This solution would offer the pilot visual comfort and greater help with decision making in the case of danger. The WXR meteorological application can also be overlaid on the cartographic function, as well as any other applications intended to represent graphical data on a display.
Nevertheless, within the framework of a common representation of the various graphical representations, it is necessary to harmonize and therefore to synchronize the refreshes and the graphical servoings for pilot readability as regards the information presented.
The device according to the invention lies within the framework of the integration of these various functions and the harmonization and synchronization of the refreshing of the graphical representations presented to the pilot independently of the structure and of the calculation of the applications data.
In order to harmonize the integration of the aforementioned applications or of other applications earmarked for graphical representation, it is necessary to consider a reference real-time calculation cycle C0 of the avionics computer, such as defined previously, capable of providing at least the position of the aircraft and its heading to other resources. This cycle can be different depending on the avionics computers or the aircraft. It involves a calculation reference and does not constitute a restrictive datum of the device according to the invention.
Generally, the aircraft-related information, such as the system data, the trajectory, the altimetry data or the resources of said aircraft are all calculated in a cycle C2. For certain applications, in the subsequent description, it is considered that the two cycles C0 and C2 are of equal value.
Such is the case for the mapping application, which in a cycle C0, is capable of extracting the data from the digital terrain base, of generating an image and of orienting it as a function of the heading and position of the aircraft on a viewing screen.
FIG. 4 represents the example of a graphic 43 arising from the data of a TAWS application which is overlaid on a mapping of the space overflown.
The overlaying of the data of these two applications represents one case of realization among others. The structure of the data of these two applications does not restrict the range of the device of the invention.
The cartographic data arise from an application including a digital terrain database. The digital data of the TAWS application are refreshed graphically in groups of four radials in a circular manner, from left to right. At each cycle C0, four additional radials are refreshed and displayed on a display. Each radial includes a number of given digitized points which are calculated. The set of radials making up an entire image is refreshed after a cycle C1, corresponding to 100 cycles C0.
The angular space 41 occupied by four radials represents a part of the graphical representation generated by the TAWS application.
The two graphical representations of each of the applications are redisplayed at the end of their own cycle, respectively C0 and C1.
When the aircraft changes heading for example, that is to say it performs a turn, the graphical overlay produces a shearing effect 40 with regard to the different servoing cycles. Only the part of the data included in the angular sector 41 is refreshed in the same time interval as the cartographic data. But the part of the data included in the angular sector 41 as well as the other part of the TAWS data are not reoriented according to the new heading and the new position of the aircraft, calculated in a cycle C0, before the end of the cycle C1. The pilot no longer obtains a representation of the TAWS data included in the angular part where they are not yet calculated, in accordance with reality during a short moment.
A certain number of cycles later, the data included in the angular space 42, including four radials, are themselves refreshed. The radial shearing occurs between the data refreshed on the left part of the drawing and those which will be refreshed in the forthcoming cycles in the right part of the drawing.
Despite the gain of information on one and the same screen, the shift of graphical overlay introduces discomfort for the pilot.
The refreshing by parts, and therefore over several cycles of calculations, of the TAWS data is independent of the mapping.
In the same manner, FIG. 5 represents one and the same overlay 43 of the data arising from the TAWS application and of the mapping application. A turn of the aircraft introduces a shift of the graphics. The zone 52 represents a danger-free zone, corresponding to a high altitude of the aircraft relative to the ground. This zone corresponds to the valley 51 of the mapping. It is markedly apparent that these two zones are not overlaid in this calculation cycle. A slippage originating from the change of heading of the aircraft is observed.